The invention is in the field of multiple photoflash lamp units, such as planar arrays.
The FlipFlash type of photoflash array, disclosed in U.S. Pat. No. 3,937,946 to Weber, is a multiple flash lamp unit that can be connected to a camera in different orientations in each of which a different group of the flash lamps is relatively farther from the camera lens axis than are the other lamps of the unit. The lamps and electrical circuitry are arranged so that in any of the orientations of the unit with respect to the camera, only the group of lamps relatively farther from the lens axis can be flashed. The purpose of such an arrangement is to position the "active" group of flash lamps farther above the camera lens in order to reduce the possibility of a "red-eye" effect that causes the pupils of a person's eyes to appear red or pink in flash pictures taken when the flash lamp is close to the camera lens.
Such flash units employ high voltage types of flash lamps which are flashed by a high voltage pulse (1000 or 2000 volts, for example) of low energy, and are prone to electrostatic firing of one or more lamps if the flash unit is touched by or brought into close proximity to a person or object having an electrostatic charge. Such undesirable accidental flashing of lamps can also occur if the flash unit housing, which usually is made of a plastic material, acquires an electrostatic charge and a connector terminal is touched by or brought into close proximity to a person or object. The problem can also occur, and can be more severe, if both the plastic housing and the person or object near to or touching a connection terminal are electrostatically charged with relatively opposite polarities.
Various ways have been devised for reducing the likelihood of accidental flashing of lamps by electrostatic charges, for example by providing an electrically conductive shield adjacent to the circuit board and electrically connecting the shield to the common or "ground" electrical part of the circuitry of the circuit board. The shield increases the stray capacitance to surrounding space so that electrostatic charges applied to the flash array tend to dissipate into surrounding space rather than through the flash lamps. U.S. Pat. No. 3,935,442 to Hanson discloses a flash array having a shield in the form of a conductive reflector unit connected to electrical ground of the circuit board. U.S. Pat. No. 3,941,992 to Blount et al. discloses a flash array having an electrically grounded shield adjacent to or on the rear surface of the circuit board. U.S. Pat. No. 4,019,043 to Blount discloses a flash array having a metal foil sheet shield behind the circuit board and electrically grounded by means of eyelets through the circuit board, and the above-referenced patent application discloses a similar arrangement but with a different way of grounding the shield. U.S. Pat. No. 4,036,578 to Herman discloses a flash array having a sheet shield that is electrically grounded by being in contact against bent-over eyelets which pass through the board and connect a lead-in of each flash lamp to electrical ground of the circuit.